Dyeing cellulose derivatives in the presence of inorganic thiocyanates and organic acids



i atenteci Aug. 15 1956 DYEING oELLU os DERIZA'EHESIINTHIQ rREsENoE FINORGANIC, 'rn ooyg v- 'ATES AND ORGANIC gnes George W.Se'ymour andGeorge C. Ward, 0.11m: berland Md assignors to Celanese Corporation ofAmerica a corporation o; Delaware "No Drawing, Application April 16,194?, $31?! 1 wee-5a) -6 Glaims.

'This invention relates to the dyeing of cellulose acetate orotherorganic derivative of cellulose textile materials and relates moreparticularly to an improved process for the dyeing of said textilematerials in shades which are of improvedifastness=to light and to acidfading.

object of this inyentionis the provision of an improved dyeing processwhereby cellulose acetate or-other organic *derivative or cellulosetextilemater'ials may .be :dyed rapidly in deep,

level shades which are of unusual resistance both to light and to acidfading.

' Another object of this invention is to provide animproved solventdyeing process for the rapid dyeing ofcelluloseacetate'or'other organicderives tive of cellulose textile mater-ials, wherein the dyebathemployed is free of inflammable organic solvents yet highly effectivewhen applied'to cellulose acetate or other organicderivative-fofcellulose textile materials :by dyeing methods involvingmechanical"impregnation. "(other objects 'of'ithis invention will appearfrom the'follow'ing detailed description.

In dyeing textile materials having a basis of cellulose acetate .orother "organic derivative of cellulose, it has been found that'these'materials are dyed more slowlythan othertextile materials since theyare less absorbent and the dye liquor in'the bath does not penetratethem asrapidly or as completely as it does other textile materials.Consequently, i'n'or cler to obtain satisfactory-dyes ings in deep,non-fugitive shades/long periods of'immersion and manipulationwere'zrequired. Extended dyeing processes are obviously uneconomical andmethodswhereby cellulose acetate or other organic derivativeofscellulosetextile materials may be dyed rapidly .bya continuous process are ofgreat economic value, :since a continuous process enables the costxofdyeing to be substantia'lly decreased. In'the-case-oi certain dyestuifs,such as acid. or direct cotton: dyestuffs, for example-it is well knownthat the same have little or no affinity for cellulose acetate or otherorganic derivative of cellulose textile -materials when-the usualmethods of applying said dye: stuffs are employed. However, thesedyestuffs possess many valuable characteristics andsu-itable'methods ofapplying thesame *to'cellulose acetate or other organic derivative ofcellulose materials in a rapid and efiicient manner-have been-the objectof much investigation.

' :We have nowfoundthat textile materials hav-r ing'sa basisofzcelluloseacetate or .other organic derivative. of cellulose may be 'Jdyed veryrapidly byflmechanical impregnation methods employing 7 various types ofdyestufis ,:-and deep, levelshagles n uai e ne sits aci -and ishthdinsbe ob ained if the dye ba h emp o ed comp an aqueous solution of adyestufi for said cellul e e a r o r orsanicideri a ive 0 qeiiullesematerial containin a low r'aliphati acid'ar d no eanicsweilineasen forthe or an- Q deityative of 'cellulosematerial. By employing our novel onbaths and appl ing the ome a mechanical impregnation :-1 nethods, dyeingbe :effiectedin a matter of seconds. Asa result of this novel advance inthe art, continuous prose esses ior dyeing'ueellulose acetate 1 .1 otherorganic derivative of cellulose textile: materials are quite feasible.The dye textile'materials may be Washed orscoured' immediately afterdyeing withouta y intermediate drying ;or the use of 'skying rolls toinsure thorough penetration or absolfptionp f the dyestufi'byeprojlong-ing the timep f contact of the dye liquor-with the textilematerial. Thus, the dyeing operation may be carried out as .a continuousprocess with :a substantial reduction in cost dueto the greatlyincreased capacity-which is achieved because of the extremely rapidcontinuousnature of'the process.

Any suitable *lower aliphatic acid may 'be e ployedin formingour-noveldye bath. Examples of "these lower aliphatic acids are acetic "acid.propionic acid and butyricca-cid. 'Thewacid may be employed amountsvarying from about, 20 to 46 %"son"the=weight of the aqueousbath. Opti:mum results are: achieved employing-acetic-iacid inlan amountoifromabout :25 1:0 :by Weight of :the dyebath.

:As examples of inorganic' swelling agents ifor the.organicderivativevof cellulose-materials, :there may bementioned saltsof thiocyanic :acid, .such aspammoriium thiocyanate, sodium thiocyanateand' potassium thiocyanate. Optimum results'sar'e achieved employingsodium'thiocyanate. The ine organic swelling :agentrnay be presentinamonnts off-rom :2 to 30% on the 'i'veight of ithedye bath.Preferably,--=we employ thethiocyanate's :in amounts 50f from about :3to 10% 'by weigh't.

Various dyestuffsfor' l-organic Iderivative 'of cle lulose materials'may 'beiemp1oyed in accordance with .our novelprocess. As-stated, thesedye stufis may be acid dyes which are 'ordinarily' used for the dyeing.of wool and direct cotton dyes which are ordinarily used for dyeingcotton and whic'ha do'znot possess any substantial a-fifinity fororganic 'derivativeszof cellulose materials-when applied 'by the methodsusually employed ior applying said acid or' direct cotton dyes'tuffs. Wemay' lalso employ these dy'es which are relatively insoluble in waterand which are usually applied to organic derivative of cellulosematerials in the form of aqueous dispersions. Mixtures of thesedyestuffs may also be employed. When these dyestufis are applied to thecellulose acetate or other organic derivative of cellulose textilematerials by mechanical impregnation methods in aqueous lower aliphaticacid solutions containing an inorganic swelling agent for saidmaterials, in accordance with our process, the resulting dyeings are ofuniform depth and brilliance and are obtained with a relatively shortimmersion time. Little or no wash-down of the shade in subsequentwashing and finishing operations is observed in the case of fabrics dyedby our novel process.

The amount of dyestufi dissolved in the dye bath will, of course, varywith the final shade desired in the material which is being dyed and maybe from as low as 0.01% up to 8% based on the weight of the material tobe dyed.

The dye liquor may be applied to the organic derivative of cellulosetextile materials by padding, spraying or by other convenient method ofmechanical impregnation and at a temperature of 20 to 60 C. Preferably,we maintain the dyebath at about 25 C. Thus, as a continuous process, afabric may be unwound from a roll, passed through a solution of thedyestufi, then between nipping rolls of a padding mangle which areadjusted to remove excess dye liquor from the fabric, and the fabricthen subjected directly to washing or scouring. The duration of theimmersion of the fabric in the dye liquor is relatively short and may befrom 1 to seconds. If desired, the fabric may be processed through thepadding mangle at speeds ranging up to 60 yards per minute.

Our process is applicable not only to the dyeing of fabrics butparticularly valuable results are obtained when other organic derivativeof cellulose textile materials such as staple fiber, in the form of atop or roving, or a tow of continuous filaments is dyed in accordancewith our invention. Not only may faster and more uniform dyeings beobtained, but, as in the case of fabrics increased production may beachieved along with a substantial reduction in the amount of dyestuiTnecessary to obtain a desired shade.

The organic derivative of cellulose fabrics, staple fiber yarns or othertextile materials dyed in accordance with our process may have a basisof cellulose esters or cellulose ethers. Examples of cellulose estersare cellulose acetate, cellulose propionate, cellulose butyrate, andmixed esters such as cellulose acetate-propionate and celluloseacetate-butyrate, while examples of cellulose ethers are ethyl celluloseand benzyl cellulose. The materials may be mixed materials containingorganic derivatives of cellulose and yarns. or fibers of other materialssuch as cotton, silk, wool, .or regenerated cellulose and in this waydiflerential dyeings may be obtained where the dyes used have anafilnity for only one of the components of the mixed textile material.

- In order further to illustrate our invention but without being limitedthereto, the following examples are given:

Example I A previously scoured fabric of a satin construction containingcellulose acetate yarn in both warp and filling is passed through a bathcontaining 1 Artol Blue GL (Color Index 833), 30% aceticacid and 5%sodium thiocyanate at 25 C.

and then squeezed through padding rollers to give expression. It is thenrinsed thoroughly in cold water and given a light soaping. The fabric isthen dried on a tenter frame. The speed of the machine is so adjustedthat the time between the entrance of the fabric into the dye bath andits entrance into the rinse bath is 6 seconds. A medium blue dyeing isobtained of excellent light fastness and resistance to gas fading.

Example II A previously scoured fabric of a taffeta constructioncontaining cellulose acetate yarn in both warp and filling is paddedwith a dye bath containing 2% Amanil Chrysophenine G Ex. Conc. (ColorIndex 365), 30% acetic acid and 5% sodium thiocyanate for 6 seconds at25 C. and then rinsed immediately in cold water, soaped lightly anddried. The resulting fabric is dyed a golden yellow of excellent lightfastness, washing fastness and resistance to gas fading.

Example III A cellulose acetate tow comprising a plurality of filamentsof 57,000 total denier is passed through a dye bath containing 0.033%Vitrolan Yellow GR, 0.033% Vitrolan Orange R, 0.017% .(said Vitrolans,which are also known as Neolans, being premetallized and chromedyestuffs) Artol Blue GL, 30% acetic acid and 5% sodium thiocyanate for6 seconds at 25 C. and then rinsed immediately in cold water. The tow isdyed a green shade of good fastness to light, washing and goodresistance to atmospheric fading. The tow may be cut into staple'flbersand spun into yarns suitable for the production of carpeting or menssuiting fabrics due to the fastness of the dyeing.

It is to be understood that the foregoing detailed description is givenmerely by way of illustration and that many variations may be madetherein without departing from the spirit of our invention.

Having described our invention, what we desire to secure by LettersPatent is:

1. Process for the coloration of organic derivative of cellulose textilematerials, which comprises mechanically impregnating said textilematerial with a dyebath consisting of water, a dyestufi forsaid organicderivative of cellulose material, at least 20% by weight of a loweraliphatic acid, and from 3 to 10% of a salt of thiocyanic acid which isa swelling agent for the organic derivative of cellulose material.

2. Process for the coloration of cellulose acetate textile materials,which comprises mechanically impregnating said textile material with adyebath consisting of water, a dyestuff for said cellulose acetatematerial, at least 20% by weight of a lower aliphatic acid, and from 3to 10% of a salt of thiocyanic acid which is a swelling agent for thecellulose acetate material.

3. Process for the coloration of cellulose acetate textile material,which comprises mechanically impregnating said textile material with adyebath consisting of water, a dyestuff for the cellulose acetatematerial,.2.0 to 40% by weight of acetic acid and from 3 to 10% byweight of sodium thiocyanate.

4. Process for the coloration of organic derivative of cellulose textilematerials, which comprises passing textile material, having a basis ofan organic derivative of cellulose, through a dyebath, consisting ofwater, a dyestuff for the organic derivative of cellulose textilematerial, from 3 to of a salt of thiocyanic acid which is a swellingagent for the organic derivative of cellulose textile material and atleast 20% by weight of a lower aliphatic acid, for a period of from 1 toseconds, subjecting the so-treated textile material to pressure, andrinsing and then drying dyed textile material.

5. Process for the coloration of cellulose acetate textile materials,which comprises passing textile material, having a basis of celluloseacetate, through a dyebath, consisting of water, a dyestuff for thecellulose acetate textile material, from 3 to 10% of a salt ofthiocyanic acid which is a swelling agent for the cellulose acetatetextile material and at least by weight of a lower aliphatic acid, for aperiod of from 1 to 15 seconds, subjecting the so-treated textilematerial to pressure, and rinsing and then drying dyed textile material.

6. Process for the coloration of cellulose acetate textile materials,which comprises passing textile material, having a basis of celluloseacetate, through a dyebath, consisting of water, a dyestuff for thecellulose acetate textile material, 3 to 10% by weight of sodiumthiocyanate and at least 20 to by weight of acetic acid, for

. a period of from 1 to 15 seconds, subjecting the sotreated textilematerial to pressure, and rinsing and then drying dyed textile material.

GEORGE W. SEYMOUR. GEORGE C. WARD.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,398,357 Briggs et a1 Nov. 29,1921 1,963,974 Ellis June 26, 1934 2,053,276 Ellis Sept. 8, 19362,328,682 Schnegg Sept. 8, 1943 2,344,973 Croft Mar. 28, 1944 2,347,001Schnegg Apr. 18, 1944 2,365,809 Ellis Dec. 26, 1944 2,380,503 Croft eta1 July 31, 1945 2,428,834 Croft et a1 Oct. 14, 1947 2,428,835 CroftOct. 14, 1947 FOREIGN PATENTS Number Country Date 285,948 Great BritainFeb. 13, 1928 500,960 Great Britain Feb. 17, 1939 576,927 Great BritainApr. 1946 OTHER REFERENCES Rayon Textile Monthly, Sept. 1946, (496)

1. PROCESS FOR THE COLORATION OF ORGANIC DERIVATIVE OF CELLULOSE TEXTILEMATERIALS, WHICH COMPRISES MECHANICALLY IMPREGNATING SAID TEXTILEMATERIAL WITH A DYEBATH CONSISTING OF WATER, A DYESTUFF FOR SAID ORGANICDERIVATIVE OF CELLULOSE MATERIAL, AT LEAST 20% BY WEIGHT OF A LOWERALIPHATIC ACID, AND FROM 3 TO 10% OF A SALT OF THIOCYANIC ACID WHICH ISA SWELLING AGENT FOR THE ORGANIC DERATIVE OF CELLULOSE MATERIAL.